Conformational dynamics of alpha-synuclein:insights from mass spectrometry

The aggregation and deposition of alpha-synuclein in Lewy bodies is associated with the progression of Parkinson's disease. Here, Mass Spectrometry (MS) is used in combination with Ion Mobility (IM), chemical crosslinking and Electron Capture Dissociation (ECD) to probe transient structural elements of alpha-synuclein and its oligomers. Each of these reveals different aspects of the conformational heterogeneity of this 14 kDa protein. IM-MS analysis indicates that this protein is highly disordered, presenting in positive ionisation mode with a charge state range of 5 <= z <= 21 for the monomer, along with a collision cross section range of similar to 1600 angstrom(2)). Chemical crosslinking applied in conjunction with IM-MS captures solution phase conformational families enabling comparison with those exhibited in the gas phase. Crosslinking IM-MS identifies 3 distinct conformational families, Compact (similar to 1200 angstrom(2)), Extended (similar to 1500 angstrom(2)) and Unfolded (similar to 2350 angstrom(2)) which correlate with those observed in solution. ECD-Fourier Transform-Ion Cyclotron Resonance Mass Spectrometry (ECD-FT-ICR MS) highlights the effect of pH on alpha-synuclein structure, identifying the conformational flexibility of the N and C termini as well as providing evidence for structure in the core and at times the C terminus. A hypothesis is proposed for the variability displayed in the structural rearrangement of alpha-synuclein following changes in solution pH. Following a 120 h aggregation time course, we observe an increase in the ratio of dimer to monomer, but no gross conformational changes in either, beyond the significant variations that are observed day-to-day from this conformationally dynamic protein

Half a century of amyloids: past, present and future

Amyloid diseases are global epidemics with profound health, social and economic implications and yet remain without a cure. This dire situation calls for research into the origin and pathological manifestations of amyloidosis to stimulate continued development of new therapeutics. In basic science and engineering, the cross-ß architecture has been a constant thread underlying the structural characteristics of pathological and functional amyloids, and realizing that amyloid structures can be both pathological and functional in nature has fuelled innovations in artificial amyloids, whose use today ranges from water purification to 3D printing. At the conclusion of a half century since Eanes and Glenner's seminal study of amyloids in humans, this review commemorates the occasion by documenting the major milestones in amyloid research to date, from the perspectives of structural biology, biophysics, medicine, microbiology, engineering and nanotechnology. We also discuss new challenges and opportunities to drive this interdisciplinary field moving forward. This journal i

Photophysics of Supercomplexes. A Laser-Induced Optoacoustic Study of the Adducts formed between Ru(bpy)(CN)42- and Polyaza Macrocycles

In aqueous solution, the energy content of the triplet metal-to-ligand charge transfer _3MLCT. state, as deter- mined by laser-induced optoacoustic spectroscopy, for both 1:1 supercomplexes _wRu_bpy._CN.4 xPw24xane-wN6H6 x44q and wRu_bpy._CN.4xPw32xane-wN8H8x46q are similar to that for free Ru_bpy._CN.42y _223"8 kJrmol.. The reduction of the structural volume change upon formation of the 3MLCT state in the order Ru_bpy._CN.2y _14.9 mlrmol., _wRu_bpy._CN. x 4 4 Pw32xane-wN8H8x46q _5.2 mlrmol. and _wRu_bpy._CN.4 xPw24xane-wN6H6 x44q _2.5 mlrmol. is attributed to the rigidity of the macrocycle cavity. The 3MLCT state lifetime increase from 104 ns for Ru_bpy._CN.2y to 150 ns for _wRu_bpy._CN. xP 4 4 w24xane-wN6H6x44q and 182 ns for _wRu_bpy._CN.4 xPw32xane-wN8H8x46q is due to the decrease in the number of CN groups free to form hydrogen bonds with water: four, one, and none, respectively